The present invention relates to a sewing machine provided with two needle rods or bars and a device for engaging and disengaging the two shafts connecting the respective needle rods of the sewing machine, so that both the needle rods receive the known alternating movement or one of these does not receive the said movement, depending on whether the said device is in the engaged or disengaged position.
In this way, using only one machine, it is possible to perform two lines of stitches at a distance from each other on an article of clothing and interrupt one of the said lines of stitches for any chosen section. In particular, it is possible to start with a single line of stitches performed by one needle rod while the other one remains disengaged for a certain section, after which it is possible to continue with both the lines of stitches.
The above cannot be achieved using two-needle sewing machines of the known art. Instead, a sewing machine with one needle is used, performing, in a known manner, one line of stitches at a time and hence taking twice as much time.
The object and technical problem of the present invention have been previously those of designing a sewing machine with two needles which is provided with a device such that it is able to perform two lines of stitches simultaneously, with the possibility of interrupting one of them for any chosen sections, that is, by disengaging one needle rod with respect to the other one.